feat: add blurhash package

Author: DaveyEke

bun.lock

@@ -1,4 +1,4 @@
-global.RN_HARNESS = {
-  appRegistryComponentName: 'NitroImageExample',
-  disableViewFlattening: false,
-}
+global.RN_HARNESS = { 
+    appRegistryComponentName: 'NitroImageExample',
+    disableViewFlattening: false,
+  };

example/.harness/manifest.js

@@ -0,0 +1,77 @@
+import { describe, expect, it } from 'react-native-harness'
+import { Images } from 'react-native-nitro-image'
+import {
+  BlurHash,
+  getAverageColor,
+  isBlurhashValid,
+} from 'react-native-nitro-image-blurhash'
+
+const RED = { r: 1, g: 0, b: 0, a: 1 }
+const BLUE = { r: 0, g: 0, b: 1, a: 1 }
+
+describe('BlurHash - round-trip', () => {
+  it('encodes a small image to a BlurHash string', () => {
+    const source = Images.createBlankImage(64, 64, true, BLUE).resize(32, 32)
+    const hash = BlurHash.encode(source, 4, 3)
+    expect(typeof hash).toBe('string')
+    expect(hash.length).toBeGreaterThan(0)
+    expect(isBlurhashValid(hash)).toEqual({ isValid: true })
+  })
+
+  it('decode produces an Image of requested dimensions', () => {
+    const source = Images.createBlankImage(64, 64, true, BLUE).resize(32, 32)
+    const hash = BlurHash.encode(source, 4, 3)
+    const decoded = BlurHash.decode(hash, 16, 24, 1)
+    expect(decoded.width).toBe(16)
+    expect(decoded.height).toBe(24)
+  })
+
+  it('async variants round-trip encode + decode', async () => {
+    const source = Images.createBlankImage(64, 64, true, RED).resize(32, 32)
+    const hash = await BlurHash.encodeAsync(source, 4, 3)
+    const decoded = await BlurHash.decodeAsync(hash, 32, 32, 1)
+    expect(decoded.width).toBe(32)
+    expect(decoded.height).toBe(32)
+  })
+})
+
+describe('isBlurhashValid', () => {
+  it('returns isValid:true for a freshly produced hash', () => {
+    const source = Images.createBlankImage(64, 64, true, BLUE).resize(32, 32)
+    const hash = BlurHash.encode(source, 4, 3)
+    expect(isBlurhashValid(hash)).toEqual({ isValid: true })
+  })
+
+  it('rejects a malformed hash with an errorReason', () => {
+    const result = isBlurhashValid('bad')
+    expect(result.isValid).toBe(false)
+    if (!result.isValid) {
+      expect(result.errorReason.length).toBeGreaterThan(0)
+    }
+  })
+})
+
+describe('getAverageColor', () => {
+  it('returns r/g/b channels in [0, 1] for a valid hash', () => {
+    const source = Images.createBlankImage(64, 64, true, BLUE).resize(32, 32)
+    const hash = BlurHash.encode(source, 4, 3)
+    const color = getAverageColor(hash)
+    expect(color).toBeDefined()
+    if (color != null) {
+      for (const channel of [color.r, color.g, color.b]) {
+        expect(channel).toBeGreaterThanOrEqual(0)
+        expect(channel).toBeLessThanOrEqual(1)
+      }
+    }
+  })
+
+  it('returns undefined for a too-short hash', () => {
+    expect(getAverageColor('short')).toBeUndefined()
+  })
+})
+
+describe('BlurHash.clearCosineCache', () => {
+  it('does not throw', () => {
+    expect(() => BlurHash.clearCosineCache()).not.toThrow()
+  })
+})